Means for controlling the supply of liquid fuel to internal-combustion prime movers



May 18, 1954 LEAD/NG- FROM 19 BLOWER FUEL O. N.-"LAWRENCE MEANS FORCONTROLLING THE SUPPLY OF LIQUID TO INTERNAL-COMBUSTION PRIME MOVERSFiled May 12, 1950 CONNECTED 7b BLowE/e INLET 9 lag-3 com/5:711:

w BLOWER A O U TL E T Patented May 18, 1954 MEANS FOR CONTROLLING THESUPPLY OF LIQUID FUEL TO INTERNAL-COMBUSTION PRIME MOVERS Owen NapierLawrence, Dorridge, England, as-

signor to Joseph Lucas Limited, Birmingham,

England Application May 12, 1950, Serial No. 161,511

Claims priority, application Great Britain May 16, 1949 Claims.

This invention relates to means for controlling the supply of liquidfuel to internal combustion prime movers, such as jet-propulsionengines, gas turbines or the like, and to which air is supplied by ablower.

The object of the invention is to provide improved fuel regulating meansof the kind which is responsive, at least in part, to blower-airpressure.

In the accompanying sheet of explanatory drawing:

Figure 1 is a part sectional view illustrating diagrammatically fuelregulating means according to the invention in association with avariable delivery fuel pump of the swash-plate type.

Figures 2 to 6 are similar sectional views illustrating respectivelyfive modifications of the invention.

The variabl delivery fuel pump shown in Figure 1 is of well known formand comprises a rotary body part a in a casing b; a plurality ofspring-loaded plungers c mounted in bores in and extending from one endof thebody part, an angularly adjustable swash plate d by which theplungers are actuated during rotation of the body part, a fuel inletpassage 6, and a fuel delivery passage j. The body part a is adapted tobe driven in any convenient manner by the prime mover (not shown) to besupplied with fuel by the pump, the prime mover being supplied with airby a blower (also not shown).

Atone end of the pump casing b is a cylinder 9 having closed ends.Within the cylinder 9 is arranged a piston h loaded by a spring 2, andextending from one side of this piston and through one end of thecylinder is a rod which is connected to the swash plate (1. One end ofthe cylinder g is in free communication with the pump delivery passage fthrough a passage is. The other end of the cylinder g (which contain thespring 2) communicates with the pump delivery passage through arestricted passage m, and also communicates with a small vent n which atits outer end forms a seating for a closure member 0 on one end of alever p in a chamber q. When the vent n is closed the piston h is movedby its loading spring i in the direction for causing the swash plate (1to increase the pump output, and when the vent is open the piston ismoved by fluid pressur in the direction for causing the swash plate toreduce the pump output. The lever p carrying the vent-closure member 0 ipivotally supported at a position between its ends by a partition rdividing the interior of the chamber q into two compartments s, z. Thevent n is formed in the wall of the compartment .9 which is providedwith an outlet u, and contains a spring 11 which acts on the lever 10 inthe direction for closing the vent. The other compartment t is dividedinto two sub-compartments by a diaphragm w adapted to act on the lever pin the direction for opening the vent, and these two sub-compartmentscommunicate respectively with adjacent ends of two passages ac, y. Theother end of the passage as communicates with the pump delivery passage1' at a position between the pump outlet and a chamber 2 through whichfuel from the pump delivery passage can flow to the nozzles 2 of theprime mover, the fuel flow through this chamber being controlled by aslidably adjustable throttle valve 3 adapted to co-operate with aseating 4 in the chamber. The other end of the passage y communicateswith the chamber a at the outlet side of the seating 6. Consequently,the pressure difference set up by the throttle valve 3 is communicatedto the diaphragm to acting on the lever 10, and the movement of thevent-closure member 0 (which controls the output of the pump) depends onthis pressure difference.

In carrying the invention into effect as shown in Figure 1, there isemployed a stepped cylinder 5 which is closed at its ends, and in whichare slidable two integral or interconnected pistons 6, "l of differentdiameters. At a position between the pistons 6, l the cylinder 5 isconnected by a passage 8 to the throat Q of a Venturi duct Ill throughwhich the air from the blower (not shown) is caused to flow in thedirection of the arrow, this passage being connected to the throat at aposition centrally between the ends of the throat. The end of thecylinder 5 at the outer side of the larger piston l is connected to theVenturi duct i t at the exit side of its threat 9 by a passage i l. Theother end of the cylinder 5 is connected by passages i2, it to theVenturi duct ID at the approach side of its throat 9. The exit side ofthe duct ill leads to a region in which the pressure is low relative tothe blower delivery pressure, for example it may be open to atmosphere.

Coaxially with the cylinder 5 is provided another cylinder M whichcontains a piston valve [5 connected to the pistons t, i. Near one endthe valve cylinder I 2- is connected by the passage [3 to the Venturiduct is at the approach side of the throat 9, and also to a closedchamber it containing an evacuated and deformable capsule I! which isconnected to and adapted to operate the throttle valve 3 abovementioned. Alternatively the capsule 11 may be utilized for actuatingany other appropriate controlling member in a fuel supply system. At aposition spaced from the passage t3 the valve cylinder lilis connectedby another passage 19 to the part of the passage l'3 between the valvecylinder and the chamber I6, and also to the throat 9 of the Venturiduct ID at a position between the center and the approach end of thethroat. If desired the pistons 6, I may be loaded by a spring 20 actingon the outer side of the larger piston l.

The arrangement is such that below a given ratio of air pressuresactingv on the pistons 8, l", the piston valve l5 establishescommunication between the capsule chamber 16 and the Venturi throat 9through the medium of the passage I9 and a part, of the passage I3, andabove the said ratio the piston valve establishes communication betweenthe capsule chamber and the Venturi duct It at the approach side of itsthroat through the medium of the passage [3.

Since the exit side of the Venturi duct is is open to a low oratmospheric pressure region, the pressure in the throat 9 will always bea predetermined part or fraction of the blower pressure applied to theentrance side of th duct, and the throat pressure will consequently riseas the blower pressure rises. With the'priine mover at rest, the valveit will occupy the position shown in Figure 1 due to the action of thespring 2t,'with the capsule chamber it in communication with the throat,s through the passage 19. When the prime mover is started up, thiscondition is maintained since the blower pressure acting through thepassage E2 on the left hand side of the small piston 6 i unable toovercome the force acting in the opposite direction due to the lowpressure from the exit side of the duct it acting through the passage l5 on the right hand side of the large piston I. When the prime moverattains a predetermined speed and the ratio between the blower pressureat the entrance to the duct Iii and the pressure in the exit of the ductis exceeds a given value, the preponderating pressure acting through thepassage E3 on the left hand side of the small piston B will move thepistons and valve to the right, since the low pressure acting throughthe passage I l on the right hand side of the large piston '1 remainssubstantially constant. This change in the position of the valve itcloses the passage [9 and opens the passage l3, thereby establishingcommunication between the full blower pressure at the entrance end ofthe duct Ill and the capsule chamber it, whereby the fuel controllingthrottle 3 is actuated to increase the supply of fuel to th burners ofthe prime mover.

The mode of applying the various pressures to the pistons 6, l in orderto obtain the required movement of the piston valve can be varied in anumber of ways example of which are shown in Figures 2, S and 4.

In the example shown in Figure 2, the cylinder 5 is connected at aposition between. the pistons 6, l to the Venturi duct it at theapproach side of its throat 9 by a passage 2!. The end ofthe 7 cylinder5 at the outer side of the larger piston l,

is connected by a passage 22 to the Venturi throat 9 at a positioncentrally between the ends of the throat. The other end of the cylinder5 at the outer side of the smaller piston 6, is connected by a passage23 to the Venturi duct i 6 at the exit side of its throat. Near one endthe valve cylinder i4 is connected by a passage 24 to the capsulechamber above mentioned, and also to the Venturi throat 9 at a'positionbetween the entranceend and the center of the throat. At a positionspaced from the passage 24 the valve cylinder I4 is connected by apassage 25 to the passage 2I, and also to the passage 24 at a positionbetween the valve cylinder and the capsule chamber. If desired thepistons 6, I may be loaded by a spring 26 acting on the outer side ofthe smaller piston 6. In this example the pistons and valve occupy theposition shown in Figure 2 when the blower delivery pressure andconsequently the speed of the prime mover is within the lower range, andupon the blower delivery pressure exceeding the predetermined magnitudethe valve 1 5 is moved to the left.

Referring now to Figure 3, the cylinder 5 is connected" at a positionbetween the pistons 6. I to theventuri duct it at the approach side ofits throat 9by' passages 21, 28. The end of the cylinder 5 at the outerside of the larger piston l is connected by a passage 29 to the Venturiduct [0 at the exit side of its throat 9. The other end of the cylinder5 at the outer side of the smaller piston 5 is connected by a passage 36to the Venturi throat 9 at a position centrally between theencls of thethroat. Near one end the valve cylinder It is connected by the passage23 to the capsule chamber above mentioned, and also the Venturi duct isat the approach side of its throat 9. At a position spaced from thepassage 28 the valve cylinder it is connected by a passage 3! to thepassage 28 at av position between the capsule chamber and the valvecylinder, and also to the Venturi throat G at a position between thecenter and the entrance end of the throat. The pistons E), i may beloaded by a spring 32 acting on the outer side Of the larger piston 1.

In the example shown in Figure 4, the cylinder 5 is connected at aposition between the pistons ii, i to the Venturi duct it at the exitside of its throat 9 by a passage 33. The end of the cylinder 5 at theouter side of the larger piston l is connected by a passage 3 to theVenturi throat 9 at a position centrally between the ends of thethroat.I'he other end of the cylinder 5 at the outer side of the smaller pistonE5 is connected by passages 35, 36 to the Venturi duct ii] at theapproach side of its throat 9. Near one end the valve cylinder M isconnected by a passage 31 to the capsule chamber above mentioned, andalso to the Venturi throat 9 at a position between the center and theapproach end of the throat. At a position spaced from the passage 31 thevalve cylinder [dis connected by the passage 35 to the capsule chamber,and also to the Venturi duct In at the approach end of its throat 5. Thepistonsv E, i may be loaded by a spring 33 acting on the outer side ofthe smaller piston &.

The operation of the examples shown in Figures 2 to 4 is similar to thatof the example shown in Figure l. 7

Instead of employing a pair of integral or inter-- connected pistonsarranged in a stepped cylinder as in the examples above described, I mayemploy a single piston 39 arranged in a cylinder 4i]. of. uniform bore,as shown in Figure 5, for actuating thepiston valve 55. In this examplethe valve cylinder I l is connected by a passage 31 tothe capsulechamber above mentioned, and also to the Venturi duct It at the approachend of the threat 9, At a position spaced from the. passage 37 the valvecylinder is is connected by a passage 36 to the capsule chamber, andalso to the Venturi throats at a position between the center and theapproach end of the throat. Also the end of the cylinder 59 adjacent tothe valve cylinder. 14 is connected by a passage 4| to the Venturithroat 9 at a position centrally between the ends of the throat.Moreover, the other end of the cylinder 40 is connected by a passage 42to the Venturi duct I!) at the exit side of its throat. The piston 39may be loaded by a spring 43 acting on the side of the piston remotefrom the valve l5.

In all of the examples above described the positions at which theVenturi throat communicates with the associated passages may be varieddepending on the blower pressure at which the piston valve is requiredto be actuated, and on the fraction of the blower pressure required tobe initially exerted on the capsule.

Instead of employing an evacuated and deformable capsule as thefuel-controlling member in the examples above described, an equivalentdiaphragm or piston may be used.

Further instead of employing a piston or pistons for actuating the valveas in the examples above described equivalent flexible diaphragms may beused. Thus, the piston shown in Figure 5 may be substituted by adiaphragm 44 as shown in Figure 6. This diaphragm 44 divides a chamber45 into two compartments 46, 41, the compartment 46 being adapted forconnection by a passage 48 to the inlet side of the blower (not shown),and the other compartment 4'! being adapted for connection by a passage49 to the delivery side of the blower. The last mentioned compartmentcontains an evacuated and deformable capsule 50 which is connected atone end to the diaphragm 44 and at the other end to the adjacent wall ofthe chamber 45.

In operation the examples shown in Figures 5 and 6 are essentiallysimilar to the examples shown in Figures 1 to 4.

By this invention the ratio of the fuel and air supplied to an internalcombustion prime mover can be made to vary in a predetermined manner atdifferent speeds of the prime mover.

The invention is not, however, limited to the examples above described,as subordinate details may be varied to suit different requirements.

Having described my invention what I claim as new and desire to secureby Letters Patent is:

1. Fuel regulating means for use with an internal combustion prime moverto which air is supplied by a blower driven from the prime movercomprising, in combination, means for controlling the rate of flow offuel to the prime mover, a

member responsive to fluid pressure variations operatively connected tosaid means for actuating the same, a duct adapted to be connected at oneend to the blower delivery and leading at its other end to a lowpressure region such as atmosphere, said duct having therein flowrestricting means such as a Venturi throat to create thereby in the ductby the flow of air from the blower therethrough a region at a pressurewhich is a predetermined and related fraction of the blower deliverypressure, a passage affording communication for air at blower deliverypressure to said fluid pressure responsive member, a second passageaffording communication to said fluid pressure responsive member fromsaid region in the duct in which the pressure is a related fraction ofthe blower delivery pressure, valve means controlling said passages andhavingtwo positions for selectively opening one passage and closing theother, and means responsive to blower air delivery pressure foractuating said valve when said pressure exceeds a predeterminedmagnitude to close the second and open the first of said passages, andto close the first and open the second of said passages when the blowerair delivery pressure is below said magnitude, whereby difierent rangesof actuating pressures are applied to the fuel controlling pressureresponsive member according to whether the blower delivery pressure isabove or below the said magnitude and thereby the ratio of fuel and airsupplied to the prime mover is differently variable at different speedsthereof.

2. Fuel regulating means according to claim 1, in which the pressureresponsive member which actuates the fuel control means is arranged todivide a chamber into two parts, one of which parts is evacuated, andthe said first and second passages are in communication with the otherpart of said chamber.

3. Fuel regulating means according to claim 1, in which the said valvemeans comprises a slidable valve member and. the means responsive toblower air delivery pressure for actuating the said valve is situated inan enclosure provided with passages for admitting blower air pressureand air from a source at lower pressure so that said means is responsiveto the difierence between said pressures.

4. Fuel regulating means according to claim 1, in which the said valvemeans comprises a slidable valve member and the means responsive toblower air pressure comprises a flexible diaphragm arranged to divide achamber into two compartments having passage means for admitting air atblower delivery pressure to one of said compartments and for admittingair from a source at a lower pressure to the other of said compartments,and in which an evacuated anddeformable capsule situated in one of thecompartments is connected at opposite ends respectively to the diaphragmand an end of the chamher so that the diaphragm is responsive to thedifference between the air pressures acting on it and on the capsule.

5. Fuel regulating means according to claim 1, in which the said valvemeans comprises a slidable valve member and the means responsive toblower air delivery pressure for actuating the said valve is situated inan enclosure provided with passage means for admitting air at blower airpressure from one part of the said duct and for admitting air at a lowerpressure from an other part of the said duct so that the differencebetween the air pressures at the said parts of the duct is transmittedto the pressure responsive means.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,382,625 Garretson Aug. 14, 1945 2,422,808 Stokes June 24,1947 2,482,528 Wiegand et al Sept. 20, 1949 2,507,075 Wiegand May 9,1950

